There is a growing interest in the electronic display industry for high-quality, thin, shaped glass sheets, in particular, ones having a combination of flat areas and bent areas. For example, such shaped glass sheets are being demanded for use as covers of flat-screen televisions and for use as protective covers in other applications.
A flat glass sheet may be reformed into a shaped glass sheet. Various techniques for reforming flat glass sheets into shaped glass sheets are known, particularly in the context of automotive applications, e.g., windshields and side windows, and architectural applications, e.g., curved glass for architectural and commercial non-electronic displays. For example, U.S. Pat. No. 5,093,177 (Anderson et al.; 3 Mar. 1992) discloses a method of making a shaped glass sheet by pressing a recess area into a flat glass sheet, the shaped glass sheet being intended for use as a vehicle window. In the method of Anderson et al., a heater directs concentrated high temperature heat on a surface of the flat glass sheet to rapidly heat a transition section of a reform area of the flat glass sheet to its heat softening temperature. To avoid glass fracturing due to heating along a narrow band of the glass with concentrated heat, the glass sheet is preheated to an elevated temperature prior to applying the concentrated heat. After heating the transition section to its softening temperature, the reform area is positioned between and aligned with press dies. The reform area is then offset out of plane with the flat glass sheet by advancing one of the dies towards the other of the dies and pressing the reform area between the dies.
The method disclosed in Anderson et al. involves significant three-dimensional deformation in the reform area and pressing means to offset the reform area from the plane of the flat glass sheet. Such a process requires significantly decreased viscosity and a significant applied pressing force in the reform area. It is obvious to one skilled in the art that the surface state of the glass will be locally damaged under these conditions. For Anderson et al., this is not an issue since the “damaged part” will only have a mechanical role and will be hidden from observation of the fully mounted product. Such a luxury cannot be afforded in the case of a shaped glass sheet intended for use as a cover of an electronic display.